In the parent U.S. patent application Ser. No. 13/661,053, filed on Oct. 26, 2012, and entitled “GENERATION OF ULTRA-HIGH FREQUENCY SOUND”, (now U.S. Pat. No. 8,891,335) the generation of ultra-high frequency (1-10) GHz sound was disclosed. In the U.S. patent application Ser. No. 14/517,801, filed on Oct. 18, 2014 and entitled “USING TUNNEL JUNCTION AND BIAS FOR EFFECTIVE CURRENT INJECTION INTO MAGNETIC PHONON-GAIN MEDIUM” an efficient technique for injection of electrical current into sub-band having spin opposite to the direction of magnetization of the conductive ferromagnetic material was disclosed.